package day07;

import java.util.Random;

/**
 * 需求：生成?为的验证码(大写字母、小写字母、数字)*/
public class VerificationCode {
    public static void main(String[] args) {
        String code = generateVerificationCode(4);
        System.out.println("你的验证码为："+code);
    }
    /**生成随机验证码*/
    public static String generateVerificationCode(int len){
        String code = "";
        char[] chs = {'a','b','c','d','e','f','g','h','i','j','k','l','m',
                      'n','o','p','q','r','s','t','u','v','w','x','y','z',
                      'A','B','C','D','E','F','G','H','I','J','K','L','M',
                      'N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
                      '0','1','2','3','4','5','6','7','8','9'};
        Random rand = new Random();
        for (int i = 1; i <=len ; i++) {
//            int index = (int)(Math.random()*chs.length);//随机下标0-61
            int index = rand.nextInt(chs.length);//随机下标0-61
            code += chs[index];//获取随机字符并拼接到code中
        }
        return code;
    }
}
